Sierra Company incurs the following costs to produce and sell a single product. Variable costs per unit: S 10 $9 Direct materials Direct labor Variable manufacturing overhead Variable selling and administrative expenses $9 $4 $ 6 Fixed costs per year: $85,500 Fixed selling and administrative expenses 300,000 Fixed manufacturing overhead u tho a r y account at the end of the year shows a balance of $86,250 for the 3,750 unsold units